Email Volume Capacity Calculator

SMTP ThroughputInfrastructure PlanningSending CapacityMTA Configuration

Estimate your infrastructure sending capacity based on server specs, concurrency, and connection limits.

Number of IPs

Max Connections per IP

Avg Messages per Connection

Avg Delivery Time per Message (sec)

Sending Hours per Day

These calculations represent theoretical maximums. Real-world throughput depends on:

ISP throttling: Gmail limits to 5–20 connections per IP; Outlook varies by reputation
DNS lookup time: MX resolution adds latency per domain
TLS negotiation: Adds 50–200ms per connection
Retry queue depth: Deferred messages consume connection capacity

For high-volume operations, PowerMTA or Postfix with careful queue management can approach theoretical limits on warm, reputable IPs.